1. Field of the Invention
The present invention relates to a defect inspection apparatus and a method for inspecting an occurrence status of dust, dirt, other foreign matter, and surface defects such as pattern defects, when patterns are formed on the substrate and necessary components are fabricated thereon. Such fabrication processes include manufacturing processes for semiconductors, flat-panel displays such as liquid-crystal display elements, printed circuit substrates, or the like.
2. Description of the Related Art
In semiconductor-manufacturing processes, defects in pattern shape occur due to the presence of dust, dirt, and other foreign substances (hereinafter, referred to collectively as contamination) on the surface of a semiconductor substrate (wafer), and/or due to improper formation of electrical interconnection patterns. Such defects will cause improper electrical insulation of interconnections, short-circuiting, increased interconnection resistance, disconnections, improper insulation of capacitors, damage to a gate oxide film, or other defects. Contamination that sticks to semiconductor substrates occurs in various forms for a variety of reasons. For example, contamination may arise from a movable section of a transport device, from the human body, from the production of reactants in a processing apparatus due to process gas usage, or from chemicals or materials. Defects in pattern shape result from changes in process conditions during various steps of the pattern-forming process, including exposure to light, photographic processing, etching, cleaning, and so forth. In addition, during manufacturing processes for a flat-panel display such as a liquid-crystal display element, the display element may or will be unusable if pattern contamination arises or any form of pattern defect occurs during the pattern-forming process. Furthermore, the same also occurs during the manufacture of printed circuit substrates, and contamination and the abnormality of the process cause the short-circuiting, insufficient electrical contact, or disconnection of the patterns.
Techniques for detecting contamination and pattern defects on a semiconductor substrate are disclosed in JP-2000-105203-A, JP-2008-216790-A, U.S. Pat. No. 6,373,565. These existing methods are used to detect defects and contamination not having repeatability, by irradiating an upper surface of the semiconductor substrate (wafer) with laser light and after removing with a spatial filter the light exiting an repetitive pattern on the wafer, enhancing edges of the defects and contamination. JP-2000-105203-A also discloses a defect inspection apparatus that detects defects and contamination by emitting illumination light in a direction 45 degrees inclined with respect to a direction of a major rectilinear group of circuit patterns formed on the surface of the wafer, and thereby permitting no 0th-order diffracted light from the major rectilinear group to enter an aperture of an objective lens. JP-2000-105203A additionally discloses a defect inspection apparatus using a white light source and/or a deep-ultraviolet (DUV) laser light source. JP-2008-216790-A discloses a defect inspection apparatus that uses detection optics formed with an oval aperture, to achieve the mounting of a plurality of detection optics having a large numerical aperture (NA). U.S. Pat. No. 6,373,565 discloses a defect inspection apparatus using a mode-locked laser to inspect surface detects. Other related techniques include those disclosed in JP-2003-194739-A, JP-1999-045842-A, JP-2007-142052-A, JP-2011-171521-A, JP-2004-271498-A.